> Fourthly, and most importantly, as noted above: m(x) is a partition of unity: it “fits into itself”; [...] if we place a copy of m(x) at integral positions, a

> Fourthly, and most importantly, as noted above: m(x) is a partition of unity: it “fits into itself”; [...] if we place a copy of m(x) at integral positions, and sum up the results, we get a constant (unity) across all x. [...] This remarkable property can help prevent “beat” artifacts across a resized image. So, basically the reason why this works better than other visually similar filters is that it happens to satify the Nyquist ISI criterion[1]. [1]: https://en.wikipedia.org/wiki/Nyquist_ISI_criterion https://en.wikipedia.org/wiki/Nyquist_ISI_criterion